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1.
Ticks are important ectoparasites of domestic and wild animals, and tick infestations economically impact cattle production worldwide. Control of cattle tick infestations has been primarily by application of acaricides which has resulted in selection of resistant ticks and environmental pollution. Herein we discuss data from tick vaccine application in Australia, Cuba, Mexico and other Latin American countries. Commercial tick vaccines for cattle based on the Boophilus microplus Bm86 gut antigen have proven to be a feasible tick control method that offers a cost-effective, environmentally friendly alternative to the use of acaricides. Commercial tick vaccines reduced tick infestations on cattle and the intensity of acaricide usage, as well as increasing animal production and reducing transmission of some tick-borne pathogens. Although commercialization of tick vaccines has been difficult owing to previous constraints of antigen discovery, the expense of testing vaccines in cattle, and company restructuring, the success of these vaccines over the past decade has clearly demonstrated their potential as an improved method of tick control for cattle. Development of improved vaccines in the future will be greatly enhanced by new and efficient molecular technologies for antigen discovery and the urgent need for a tick control method to reduce or replace the use of acaricides, especially in regions where extensive tick resistance has occurred.  相似文献   
2.
This study assesses the effect of salinity in bioavailability and toxicity of Zn by means of laboratory bioassays by observing contamination in both sediment and water, accumulation of Zn in biological tissues, and histopathological damage in the gills and guts tissues of Ruditapes philippinarum clams, which were exposed to different types of sediments from the Gulf of Cádiz (SW Spain) as well as two dilutions of toxic mud coming from an accidental mining spill. With this objective, the coefficients of distribution (K D) for Zn between overlying water and sediments were calculated, the histopathological frequencies in the tissues of the gills and guts of clams were determined, and the biota-sediment bioaccumulation factors as well as the bioaccumulation factors were quantified in the different stations. Results showed that the greatest histopathological damages appeared when the salinity values decreased. Statistical results showed that salinity was inversely correlated with histopathological damage (p?<?0.01) for the lesion index for gills. The most outstanding results were observed in the two dilutions of toxic mud (0.3% and 7.9%) at a salinity value of 10. Salinity was inversely correlated with the concentration of Zn in biological tissues (p?<?0.05) and inversely correlated with the concentration of Zn in water and sediment. Zn mobilization to the overlying water is produced when salinity values decrease.  相似文献   
3.
Two assays were conducted to study the evolution of rye and barley phosphatases (phytase and acid phosphatase) and the degradation of its substrates (inositol phosphate esters) during seed germination. In this manner we could obtain a low-phytate, endogenous phosphatase rich ingredient to be used in animal nutrition. In the first assay, the seeds were soaked for 1 and 14 h and germinated for 3 and 5 days with and without the addition of gibberellic acid (GA3). In the second assay, the seeds were soaked for 1 h and germinated for 1, 3, and 5 days with GA3. Phytase (up to 5739 and 3151 U x kg(-1)) and acid phosphatase (up to 18288 and 3151 U x g(-1)) activities, and IP6 (6.09 and 6.01 mg x g(-1)), IP5 (0.48 and 0.48 mg x g(-1)), and IP4 (0.13 and 0.06 mg x g(-1)) were detected in ungerminated rye and barley, respectively. The germination process caused a significant increase of Phy and AcPh activities in rye (up to 112 and 213%) and barley (up to 212 and 634%) and a reduction in the phytate phosphorus content (up to 84 and 58%, respectively). Phytate phosphorus content was affected only by soaking time in the case of rye. Finally, during the course of germination, IP6 and IP5 were rapidly degraded in rye (88 and 79%) and barley (67 and 52%), and IP4 was only a short-living intermediate, which was increased during hydrolysis and degraded to IP3. In conclusion, a marked increase of Phy and AcPh activities in rye and barley with a concomitant decrease in phytate phosphorus content and an increase in the content of lower inositol phosphates were observed during the rye and barley germination.  相似文献   
4.
1. Two experiments were carried out to determine the effect of inclusion of raw (kabuli and desi) and autoclaved (desi) chickpea seeds in wheat-based starter diets in chickens grown to 28 d of age on the performance, digestive organ sizes, nitrogen-corrected apparent metabolisable energy (AMEn), ileal apparent protein and starch digestibilities (APD and ASD) and intestinal alpha-amylase and trypsin activities. 2. In the first experiment, diets were formulated to contain 0, 150, 300 and 450 g/kg of raw kabuli chickpea seeds. Increasing the proportion of seed in the diet negatively influenced body weight gain, food intake and food efficiency. The relative weights of the pancreas, liver and gizzard and the relative lengths of duodenum, jejunum, ileum and caeca were increased significantly when the chickpea seeds were included in the diets. Correspondingly, APD, ASD, alpha-amylase and trypsin activities and AMEn were reduced significantly when the chickpea seed was incorporated in the diets. 3. In the 2nd experiment, diets were formulated to contain 75 and 150 g/kg of raw and autoclaved desi chickpea seeds. Weight gain and food intake of the chicks given desi chickpea diets were significantly reduced compared with those fed on the control diet. Increasing the proportion of seed in the diet negatively influenced body weight gain, food intake and food efficiency. Moreover, a significant increment in the relative weights of liver and pancreas, and in the relative lengths of duodenum, ileum and caeca was observed when the concentration of chickpea seeds in the diets was increased. Feeding autoclaved seeds significantly increased the weight gains and the food intakes. However, food efficiency was not modified by the autoclaving. Relative weights of gizzard and liver and relative lengths of ileum were decreased significantly by the inclusion of autoclaved desi chickpea in the diet. 4. We concluded that the inclusion of kabuli (up to 450 g/kg) and desi (up to 150 g/kg) chickpea seeds produced a negative effect on the performance of the birds, and an increment in the relative weights and lengths of the digestive organs. In addition, the incorporation of kabuli chickpea produced a reduction of protein and starch digestibilities, alpha-amylase and trypsin activities, and AMEn of food compared with the birds given the control diet. Autoclaved treatment of desi chickpea improved the performance of the birds.  相似文献   
5.
Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1. 5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17 degrees15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15 degrees55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle.  相似文献   
6.
The objective of this work is to study the relation between humidity, density, porosity and shrinkage of the floodplain soil and riparian vegetation and their ability to store water. For this purpose, two locations for every type of soils were evaluated. Both were placed at the Agronomy University (Faculdade de Cidncias Agron6micas) in SAo Manuel, State of SAo Paulo, Brazil. The floodplain soil was vegetated with Southern Cattail (Typha domingensis). In both places, soil samples were collected from several depths: 0, 30, 60 and 100 cm. Results show that lower soil density values (0.15 g/cm3) with organic texture and high porosities values (up to 86.2%) were found in samples with the highest organic material content in the floodplain soil. For this field experiment, flood plains soils (characterised as basin gley soils) presented high volumetric instability with a retratibility of 67.49% and higher water storage capacities compared to riparian stands soils (characterised as fluvic neosoils).  相似文献   
7.
M. Ramos  Leal  R. H. Maribona    A. Ruiz    S. Korneva    E. Canales    T. D. Dinkova    F. Izquierdo    O. Goto  D. Rizo 《Plant Breeding》1996,115(1):37-42
After 10 years of evaluation in different locations with high levels of incidence of disease, a group of sugarcane somaclones derived from callus tissues was selected for eyespot resistance. Resistance evaluations of four somaclones were performed under field and laboratory conditions. The results confirmed the superiority of two somaclones, one resistant and one tolerant to eyespot disease. Restriction analysis of mitochondrial DN A revealed that the two somaclones had a different DNA organization which distinguished them both from each other and from the donor plant; the restriction profile was similar however to that of the resistant control done. Restriction patterns of a third somaclone, also resistant, were similar to those of the donor plant. Differences among the somaclones were also evident when using a maize ribosomal DNA probe.  相似文献   
8.
Phytase and acid phosphatase activities in plant feedstuffs   总被引:8,自引:0,他引:8  
A total of 183 samples representing 24 feedstuffs were analyzed for total phosphorus, phytate phosphorus content, phytase (Phy), and acid phosphatase (AcPh) activities with the objective to predict the capacity to hydrolyze phytic acid and to contribute to formulating environmentally adequate diets for monogastric animals. Of the cereals and cereal byproducts analyzed, only rye (5147 U kg(-)(1); 21 955 U g(-)(1)), wheat (1637 U kg(-)(1); 10 252 U g(-)(1)), rye bran (7339 U kg(-)(1); 56 722 U g(-)(1)), and wheat bran (4624 U kg(-)(1); 14 106 U g(-)(1)) were rich in Phy and AcPh activities. Legume seeds and oilseeds contained negligible Phy activity and a moderate amount of AcPh activity, except for kidney bean (33 433 U g(-)(1)) and full-fat linseed meal (13 263 U g(-)(1)). On the other hand, a significant linear regression between phytate phosphorus (y) and total phosphorus (x) was observed in cereal byproducts (R(2) = 0. 95; y = 0.8458x - 0.0367; P < 0.001) and oil seeds (R(2) = 0.95; y = 0.945x - 0.20; P < 0.001). Phy and AcPh were positively correlated with respect to phytate phosphorus in cereals, cereal byproducts, and other byproducts and negatively correlated in legume seeds and oilseeds. Except for cereals, the highest correlation between enzyme activities and phytate phosphorus was found for phytase. It is not possible to predict Phy and AcPh activities from phytate phosphorus content by linear and quadratic regressions. Finally, only highly significant and positive correlation was found between Phy and AcPh activities for cereals, cereal byproducts, and oilseeds.  相似文献   
9.
Diseases caused by arthropod-borne pathogens greatly impact on human and animal health. Recent research has provided evidence that tick protective antigens can be used for development of vaccines with the dual target of controlling arthropod infestations and reducing their vector capacity for pathogens. As reviewed herein, protective antigens such as subolesin/akirin, which are highly conserved across vector species, show promise for use in development of a universal vaccine for the control of arthropod infestations and the reduction of pathogen transmission. However, further research is needed in critical areas towards achieving this goal.  相似文献   
10.
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